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Author Topic: Goldentone Reverbmaster: Reverb on = instant feedback
MichaelM

Posts: 17
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Post Goldentone Reverbmaster: Reverb on = instant feedback
on: November 1, 2012, 14:02
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Hey

So, as shown in the I'll show you mine thread, I managed to acquire a mid 60s Goldentone Reverbmaster 40, an old Australian made valve amp. As far as I can tell, everything in the amp is original (even the 12ax7s say Made In Australia!).

Image

Everything on the amp works, except the reverb. Turning on the reverb just gives instant feedback. And not that good controllable feedback, but awful, microphone style feedback.

I tried changing the valve that drives the reverb unit, since it was really microphonic. However, that hasn't solved the problem.

Here's some more info on the amp: https://www.ozvalveamps.org/goldentone2.htm#17551759

So, where do I start trying to debug a 50 year old reverb unit?
Digital-
Larry

Posts: 192
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Post Re: Goldentone Reverbmaster: Reverb on = instant feedback
on: November 1, 2012, 17:34
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Here's what I would do.

#1 Familiarize yourself with the fact that voltages inside tube amps can be lethal and how to avoid killing yourself.

#2 Familiarize yourself with the fact that tubes get really hot and you will burn yourself if you grab a hot one without nice thick gloves on.

#3 With the power off, pull out the reverb return tube 6GWB. Looks like it might be the driver also? Turn the amp back on. You won't get any reverb but you shouldn't get any "feedback" either.

#4 With the power off, put the reverb tube back in and disconnect the reverb unit. Does it have cables that go to the rest of the circuitry with an RCA connector? If so, make a short circuit to go into the reverb return jack by taking an old RCA cable and cutting it in half, stripping the wires and twisting them together. Plug that into the reverb return jack. Turn the power back on. With the input shorted, you shouldn't be hearing any reverb (same as engaging the reverb kill switch, more or less).

#5, see if there are any markings indicating "in" and "out" on the reverb unit itself. Possibly they are swapped? (I don't really know how much it matters, but it might).

Report on your findings. Then hopefully one of the experienced tube techs will weigh in with further troubleshooting strategy.
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